System and portable device for transmitting identification signals

ABSTRACT

A system is provided with a portable device for the transmission of a signal to a second device, wherein the portable device is wearable on the body of a user. The portable device includes at least two electrodes and transmitter electronics for the generation of an electrical signal between the electrodes, such that the signal is able to be coupled by the electrodes into the body of the user and detected by at least one electrode of the second device. A portable device is distinguished in that between the electrodes are arranged component parts of the transmitter electronics and/or of an application distinct from the transmitter electronics, and/or an air gap is present.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to the communication between a sender(transmitter) and a receiver over a capacitive coupling (sometimes alsoreferred to as capacitive resistive coupling, “intrabody” coupling,RCID-coupling or PAN-coupling) in which small electrical currents whichare used for the transmission of information between the transmitter andthe receiver are generated in the human body, and/or in which thetransmitter and the receiver interact with one another over very shortdistances via electric fields.

2. Description of Related Art

This method of coupling is disclosed in the US patent specificationsU.S. Pat. Nos. 4,591,854, 5,914,701 and 5,796,827. Implementationsthereof are described in the international patent application PCT/CH2006/000518 as well as in further published specifications of variousbearers.

A particular advantage of the capacitive coupling through the human bodyor, as the case may be, over short distances is the selectivity of thedata transmission. Depending on the configuration, one can determinewith a high degree of certainty that the signal received by the receivercan only have been transmitted by the person who is situated in directproximity to or in physical contact with a receiver electrode that isdesignated for it.

A disadvantage is, among other things, that as a result of the poorsignal to noise ratio (literally: signal-interference ratio), only asmall amount of data can be transmitted. A good signal to noise ratio isonly possible with a large amplitude of the transmission signal.However, a large amplitude (i.e. high voltage) would not be tolerated bythe user. In the Swiss patent application No. 548/06, approaches aredescribed, with which these problems can be addressed. Despite these thebandwidth of the signal transmission remains limited.

The layout of the electrodes in the transmitter is important for aseffective a signal transmission as possible. According to the state ofthe art, these are designed as electrode pairs, which lie parallel andopposite one another in the manner of a plate capacitor. The electrodesshould be as large as possible so as to maximize the coupling to thebody and also to optimize the signal to noise ratio, in the situation inwhich no electrically conductive contact exists between the oneelectrode and the human body. However, these large electrodes have aproblematic effect on the design and the dimensions of the transmitter.Furthermore, they cause the power consumption of the transmitter to bequite high, so that more frequent battery changing is necessary.

It has been further seen that depending on the geometric configuration,the signal can practically cancel itself, because the electricity thatis coupled into the body by the first capacitor plate corresponds to,but has the opposite sign of, the electricity that is coupled into thebody by the second capacitor plate.

With this background in mind, it is an object of the present inventionto provide solutions for the layout of transmitter electrodes whichameliorate the above-mentioned disadvantages at least partly and whichmean a further step toward the commercial application of the technologyand its acceptance by consumers. The solutions mentioned should inparticular be usable for access control.

These objects will be fulfilled by the invention, as it is described inthe patent claims.

BRIEF SUMMARY OF THE INVENTION

A portable device according to the approach according to the inventionis, for example, wearable on the body of a user; it can be designed as acard-like identification medium, as “smart card cover”, mobiletelephone, watch, portable computer (for example of the “handheldcomputer” type) etc. It comprises at least two electrodes and means forthe creation of an electrical signal between the electrodes, such thatthe signal is able to be coupled through the electrodes to the body ofthe user and is detectable from the body by at least one electrode of asecond device. A device like this also makes possible a direct,short-range communication (not through the body), for example throughholding of the portable device in direct proximity of a receiverelectrode, i.e. applications of the invention are not limited tocoupling through the human body, but rather also extend to cases inwhich the user carries the portable device on his or her person, holdsit in the vicinity of a receiver electrode or otherwise makes itpossible that the communication between transmitter and receiver takesplace directly and not exclusively over the body.

According to an aspect of the invention, now two electrodes of aportable device (transmitter) are arranged such that between theelectrodes there are arranged either component parts of the transmitterelectronics and/or of another application distinct from the transmitterelectronics, or an air gap is present, in which such a componentpart—for example with a “smart card” as the carrier of the part—can beinserted. Combinations of “air gap” with “transmitter electronics”,“other applications” and/or “battery” are possible. A component part ofthe transmitter electronics and/or of another application distinct fromthe transmitter electronics can also indicate a hard-wired orreplaceable battery.

As component parts here are indicated active or passive, preferablyelectronic component parts, which are more than a mere separating layerbetween the electrodes, for example in particular active electroniccomponent parts such as ASICs, processors, integrated circuits, memorymodules, sender and/or receiver for contact-free informationtransmission, including active or passive RFID transponders, passivecomponent parts such as antennas, resistors, capacitors, coils, etc. oralso batteries, optical elements etc.

In particular the embodiments with a component part of anotherapplication arranged between the electrodes and the embodiments with abattery arranged between the electrodes, but also the embodiments withcomponent parts of another application arranged between the electrodes,make possible new dimensions of integration. This is also true for theembodiments with air gaps, inasmuch as a corresponding component part isinserted into the air gap.

Of course the transmitter electronics and electronic component parts forthe application which is distinct from the transmitter electronics maybe integrated together with one another in at least one unifiedcomponent—for example in an integrated circuit. The feature according tothe invention of the “component part of an application which is distinctfrom the transmitter electronics” is simply that between the electrodesare arranged electronic elements which can administrate functions thatare entirely distinct from the capacitive resistive informationtransmission and preferably from other contact-free informationtransmission methods, for example as they control or constitute thedisplay of a mobile telephone, or as they store information and/or havestored information which is not communicated with the intrabodyinformation transmission, etc.

This approach makes use of the new finding that for the transmission ofdata, the area of the electrodes is important, however not thecapacitive coupling there-between. On the contrary, it has been foundthat for a given electrode size, a large capacitance is unfavorable,because a large capacitance creates a negative effect on the life of abattery of the portable device, since larger currents flow in thegeneration of signals. Furthermore, as a result of the larger flowingcurrent of larger capacitance, the requirements on the electrodeconductivity are higher. A further finding is that the two electrodescan lie in parallel planes, but that, however, this is by no meansnecessary. So for example the electrodes can be customized to fit thehousing shape of the portable device, wherein in the design of theportable device substantially no consideration must be paid to theelectrodes.

In the case of a plate capacitor, the capacitance is proportional to thearea of the electrodes and to the dielectric constant of the materialbetween the electrodes but inversely proportional to the distancebetween the electrodes. As a result of the approach according to theinvention the two electrodes are in general farther apart from oneanother than according to the state of the art, without this precludinga compact design of the portable device. Through the larger electrodeseparation, the capacitance is limited. Particularly preferential isalso the combination with the first aspect of the invention, becausetransparent electrodes, with their comparatively limited electricalconductivity, are extremely good to use together with the approachaccording to the invention because of the small flowing currents thatresult.

In embodiments in which between the electrodes there is an air gap inwhich the components of a distinct application—for example an identitycard and/or smart card—are able to be inserted, the compatibility withexisting systems as well as backwards compatibility are also a given.

According to a special embodiment of the invention, the portable devicewith the air gap can comprise a communications interface, over whichdata can be exchanged with the application that is inserted into the airgap. Such an interface can, for example, be formed like a conventionalsmart card reader.

According to a further special embodiment, a communication link canexist between the transmitter electronics and an input unit, whereinthen the signals transmitted by the transmitter electronics can bedependent on data that are input. For example, the transmitted signalcan include a PIN, which the user previously has input in the inputunit. In this embodiment the portable device can, for example, bedesigned as a mobile telephone, wherein the input unit can correspond tothe input unit of the mobile telephone (keypad, touchscreen, voicerecognition device etc.).

According to a preferred embodiment of the invention, a portable deviceor also a receiver is distinguished in that at least one of theelectrodes is at least partially transparent.

Transparent electrical conductors, for example of very thin layers ofmetal that are vacuum-metalized or applied via a sputter depositiontechnique on a transparent substrate, or certain doped semiconductors onan oxide base (TCOs as for example ITO-layers), are currently available.For a considerable time already, these have been well-known for certainapplications, for example as components for flat-screen displays orthin-film solar cells. They have not yet been considered for informationtransmission, as they are known to have poor electrical conductivity andwould result in unacceptably large losses when used with the highfrequencies usually used in information transmission.

However, it has now been recognized that the capacitive resistiveinformation transmission is configurable such that the conductivecapacity of transparent electrodes is adequate. In particular, thecombination of comparatively low voltages (for example less than 5V oreven less than 3V) and currents and low frequencies (for example lessthan 2 MHz center frequency) allows the use of the electrodes withlimited conductive capacity.

Through this technique, many new degrees of freedom arise with respectto the design of the transmitter, until now with respect to the portabledevice the design seemed to be of little relevance, because a portabledevice of the type according to the invention is generally carried in abag or otherwise covered while worn. A further realization of theinvention is that with the introduction of transparent electrodes, thedesign possibilities of portable devices multiply considerably:

Arrangement of the electrodes as layers on a card, comprising a label orlabels—in the manner of an identification card or a “badge”, possiblywith a photo—as well as possibly comprising further functionalities. Theelectrodes can form the outermost layers—with the exception of, ifnecessary, thin protective layers—of the card. If the badge comprises anantenna for wireless communication with another communication channel,the antenna is not covered locally by at least one of the electrodes.

Arrangement of the electrodes in a holder (“shell”, “cover”) for a smartcard. Smart cards are often used as so-called “badges” for the controlof access. In the process, they are introduced into transparent holders,which for example are attachable to a piece of clothing by means of aclip and are visible from the outside. According to the first aspect ofthe invention, it is now possible to form this holder out of rigid orflexible material as part of the transmitter. This arrangement has theadditional advantage that the capacitance of the capacitor arrangementformed by the two electrodes is reduced, as will be described below inmore detail with reference to the second aspect of the invention.

Combination with a different electronic device, for example a mobiletelephone. Modern electronic devices often have large displays.According to the invention a first of the two sender electrodes can bearranged in or over the display, i.e. the display is furnished with orcovered by the transparent electrode. This also has the advantage of areduced capacitance, if the second—transparent or nottransparent—electrode is, for example, arranged in the area of a backside of the device. Furthermore this results in multifaceted possiblecombinations of the functionality, as will also be described below inmore detail with reference to the second aspect of the invention.

Furthermore the approach according to the preferred embodiment hasappealing advantages in particular for use in “access control”, in thatone does not notice that the electrodes are electrodes and thus a partof an electronic device. Rather, depending on the design, it seems to besimply a shell, a design element or another functional element.

As the portable device is a mobile telephone, the electrical supply forthe transmitter electronics can be obtained by simple means: namely asthe transmitter electronics are energized by the very powerful batteryof the mobile telephone, for example over a 3V DC supply. Thecommunication between the transmitter electronics and the remainingelectronic component parts of the mobile telephone can beaccomplished—in case these are not integrated with one another—over anyknown or yet to be developed interface, for example over a I²C data bus.

According to a further aspect of the invention, the transmitter includesan arrangement of electrodes, which contain electrode faces that are notparallel to one another.

For example, at least three electrodes can be present, wherein at leastone of the electrodes is not parallel to another of the electrodes, andwherein each of two different pairs of electrodes is acted upon by anelectrical signal.

Through this approach, according to the further aspect of the invention,the information transmission is improved. In particular, it can bepractically eliminated that with two different electrode pairs thesignal cancels itself.

In a possible embodiment of the further aspect of the invention, atleast two electrode pairs can be present, wherein the electrodes of eachelectrode pair are parallel with one another, and wherein the electrodepairs are not parallel with one another, but rather stand at rightangles or at another angle relative to one another.

As a further embodiment, three electrode faces can be present, of whichat least two are not parallel. At any one time, the signal is generatedbetween two of the three electrode faces, for example between the firstand the third electrode faces as well as between the second and thirdelectrode faces. The first and the second electrode faces can thenoptionally be wired in parallel electrically and for example even beformed in the same manner as a unified, non-planar electrode. As analternative—if the electrodes are not wired in parallel, the electrodepairs can also be alternately acted upon by the signal. Although thedata transmission speed is somewhat reduced thereby, the powerconsumption per electrode face is limited in comparison to the solutionthat is wired in parallel.

Subsequently, the power consumption of a portable device for thetransmission of signals to a second device, wherein the portable deviceis wearable on the body of a user, comprising at least two electrodesand transmitter electronics for the generation of an electrical signalbetween the electrodes, so that the signal is able to be coupled throughthe electrodes into the body of the user and is detectable from the bodyby at least one electrode of the second device, will be discussed withreference to further aspects. In each case it will be assumed that thetransmitter electronics are powered by a battery (rechargeable or notrechargeable).

The following aspects of the invention can contribute further to reducedpower consumption. Each of the aspects can be employed singly, incombination with any of the other aspects, or in combination with any ofthe previously described aspects one to four:

Use of an activity detector (movement sensor) which turns off theemission of the signal as soon as the portable device is not moved for along period of time and reactivates the signal if the device is moved.Such activity detectors are well-known and available—at low price—in themarket.

At least partial supply of the transmitter electronics and/or chargingof the battery by a solar cell and/or a generator, through whichmechanical kinetic energy is converted into electrical energy.

Larger electrode spacing of at least 1 mm, preferably at least 1.5 or atleast 2 mm.

A feature for the activation of the transmitter electronics by anexternal signal, e.g. a RFID- or UFH wake-up pulse. This wake-up pulsecan also be coded, in order to only activate an authorized transmitter.

Design of the transmitter electronics or a part thereof as an ASIC, bywhich the power requirement is optimized by only activating theabsolutely necessary electronic circuit elements and which for examplein contrast to a non-application-specific microprocessor does not queryany unused inputs.

Further there can be envisioned, also in any combinations with the aboveaspects, devices for the communication of the battery state to the user:

Transmission of a signal concerning the battery state—for example aspecific bit, if the battery is almost empty—to the receiver. By meansof this, it can then be effected that the information is conveyed to theuser and/or another entity (control center, etc.), for example throughan output device such as a display or an acoustic signal.

View of the battery state via an appropriate display feature of theportable device, for example at least an LED. Such an LED can blink, ifthe battery is nearly dead.

Provision for a “Low Comfort Mode” in which the transmitter electronicsare inactive by default and must be actively activated, for example bypressing a button. After the activation it can be imagined that after aspecific time the transmitter electronics automatically return to aninactive state. It can be imagined that the “Low Comfort Mode” is firstengaged after a second, lower voltage threshold is crossed, whilecrossing a first, higher voltage threshold would only result in theactivation of appropriate notifications (for example according to atleast one of the above aspects).

The receiver comprises at least one receiver electrode and evaluationelectronics, through which a signal that is generated by thecapacitive-resistive signal transmission between the receiver electrodeand a further electrode or between the receiver electrode and anelectric ground can be detected and evaluated.

Particularly preferable in combination with the different aspects of theinvention is the use of an information transmission method which relieson the spread spectrum method wherein the signal is transmitted as anultra-broadband signal, preferably according to the example of WO2007/112609. Ultra-broadband is defined as the use of a frequency rangeof a bandwidth of at least 20% of the center frequency or, as the casemay be, carrier frequency. According to the teaching of this document,in particular a direct sequence spread spectrum is used. The data arepreferably first modulated with a method of digital data modulation andsubsequently spectrum-spread. In WO 2007/112609, methods are alsodescribed for the analysis of a capacitive resistive signal.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, embodiments of the invention are illustrated by meansof schematic figures. Shown are:

FIG. 1 is a depiction of a portable device according to the invention;

FIG. 2 is a depiction of a further embodiment of a portable deviceaccording to the invention with an inserted smart card of a furtherapplication;

FIG. 3 is a sectional view of a portable device with smart card;

FIG. 4 is a depiction of a portable device with an RFID module;

FIG. 5 is a mobile telephone in a form according to the invention;

FIG. 6 is a schematic of the mobile telephone from FIG. 5;

FIG. 7-9 are very schematic depictions of electrode arrangementsaccording to the further aspect of the invention;

FIG. 10 is a schematic of a transmitter with possible in- and outputunits.

DETAILED DESCRIPTION OF THE INVENTION

The portable device according to FIG. 1 is substantially flat with arigid support structure 2 of, for example, plastic. The device furthercomprises a first electrode 3 and a second electrode 4. The first andsecond electrodes 3, 4 are, for example, situated on or integrated intothe outer surface of the larger faces of the support structure. They aremanufactured of electrically conductive material, for example of acopper foil, aluminum foil or possibly another electrically conductivematerial. The support structure can be a single color and/or compriseinscriptions or similar (not depicted) on its outer surfaces, such thatthe electrodes are not recognizable as such by the user. As analternative to this, the electrodes can also be manufactured from atransparent conductive material, which subsequently is furtherprocessed.

Also depicted schematically in the figure are a battery 6 and a set ofcontrol electronics 7, which comprise the means of generating acapacitive resistive signal through generation of an electrical voltagewith a pre-determined time dependence between the two electrodes 3, 4.The integrated and/or applied electronic component parts of the controlelectronics can—this is true for all embodiments of the invention—forexample include an ASIC for the control of the electrodes, EEPROM orEPROM memory, conductive pathways and/or further elements. Rather thanplastic, the support structure can be of ceramic, of fabric or of adifferent material, the important factor is simply that the twoelectrodes are electrically isolated from one another.

The support structure 2 is now designed in such a way that between theelectrodes an air gap 5 is present. Air has a very small dielectricconstant of approximately 1 (i.e. nearly the vacuum value), thereforethe capacitance of the capacitor that is created by the two electrodesis correspondingly small. Furthermore, the air gap can be used for otherpurposes, for example for the insertion of other elements.

The embodiment according to FIG. 1 comprises the portable device inaddition to a schematically-depicted interface 8, which makes possiblean exchange of data with a device that is inserted into the air gap, forexample a “smart card”. The emitted capacitive resistive signal canthereby be made dependent on data that are input to this device. It isalso possible that a data transmission object (plug connector orsimilar) of a device which otherwise remains outside the air gap can beinserted into the air gap, for example for the programming of thecontrol electronics 7.

FIG. 2 depicts an illustrative example in which one of the electrodes istransparent. The transmitter 1 is designed as a so-called “smart cardcover”. Smart card covers are known to those skilled in the art. Theyare designed as, for example, rigid, transparent shells, which forexample can be attached to a piece of clothing and in which a smart card(i.e. a card-shaped medium with memory and communicationfunctionalities) is able to be inserted.

The transmitter comprises a compartment for a battery 6 as well ascontrol electronics for the at least partially transparent electrodes 3,4, represented schematically by a chip 7. The smart card 11 is able tobe inserted into an air gap. A possible inscription area 12 of the smartcard remains visible behind the transparent first electrode 3.

FIG. 3 depicts a variant of the embodiment from FIG. 2, in which thesmart card (or as the case may be other component part of an applicationwhich is distinct from the transmitter electronics) simultaneouslyserves as RFID identification medium. In addition to the elementsalready described, one sees schematically the RFID antenna 15, whichhere is not completely covered by one of the electrodes—in the depictedexample by the transparent electrode 3. It has however been found thatin cases of transparent electrodes—for example electrodes of ITO—theRFID communication also functions if, differently than is shown in thefigure, both transparent electrodes completely cover the RFID antenna15, i.e. if the transparent electrode 3 covers the entire upper surfaceshown in the figure.

FIG. 4 depicts a further embodiment that makes possible the combinationwith RFID technology. In this embodiment an—for example passive—RFIDtransponder 21 and an RFID antenna 22 are present in the portable deviceand at least partially situated between the electrodes 3, 4. A deviceaccording to FIG. 4 can, for example, serve as a key fob, whichsimultaneously serves as an identification medium for the access control(or another use) through utilization of the capacitive resistivecoupling and as an RFID identification medium (“tag”). Since the needoften exists—this is for example the case for a key fob—to keep theouter dimensions of the portable device relatively small, the electrodes3, 4 should, if possible, cover a large portion of the device surface.Because the radio frequency signal that is generated by the electricallyconductive electrodes is shielded, the problem can arise that the RFIDsignals inside the portable device are only weak. According to FIG. 4 itis thus imagined that the fields may be aligned by use of a magneticallysoft ferromagnetic material 23 (for example a ferrite), such that theyare coupled to the front face of the portable device, as is depictedschematically by the dotted lines in FIG. 4. The RFID antenna 22 isarranged corresponding to this field alignment, for example directlywound on the ferrite 23.

The RFID transponder 21 (or as the case may be the electronics thatcontrol the RFID functionality) can optionally have a communicationslink to the control electronics 7 which operate the capacitive resistivecoupling. To this end there can be an electronic component that controlsthe RFID electronics 21 and the control electronics 7, or an integrationof the RFID electronics and control electronics into a unifiedcomponent—for example an ASIC—can be imagined.

FIGS. 5 and 6 relate to a portable device according to the inventionthat is designed as a mobile telephone 31. The first electrode 3 here isintegrated into the display and is at least in the area of the displaytransparent, while the second electrode 4 as in the previous examples oftransmitter electrodes is not necessarily transparent. The secondelectrode is situated on a reverse side of the mobile telephone (orrather as in the depicted example on the clamshell lid or on a differentpart of the mobile telephone) and can as the case may be also be formedby a conductive section of the housing. It is arranged at as large afixed distance away from the first electrode as possible. In FIG. 6, itis very schematically depicted how the transmitter electronics 7 can bein connection with the remaining mobile telephone electronics: themobile telephone supplies the transmitter electronics (3V), and acommunication link exists over a I²C interface.

As an alternative to the depicted arrangement of the electrodes, bothelectrodes—of which then none must necessarily be transparent—can bepresent in an area of the mobile telephone distinct from the display,the placement of the electrodes at least partially next to one anotheris also possible.

Through the integration of the transmitter electronics 7 in a mobiletelephone, several functionalities can be integrated together with oneanother in one portable device. The following are, for example,possible:

Dynamic alteration of the capacitive resistive transmitted data signals.The active data signal can be used as for example a PIN code, which canbe altered arbitrarily often.

Increased security can be made possible, for example through so-called“rolling codes” or other known means of secure data transmission.

An even further increased security can be achieved as the UHFtransmission means of mobile telephones (Bluetooth, 3G et.) is includedin the information transmission procedure, for example as a downlink.This makes possible for example the use of known “challenge-response”systems. A central unit can also be included into communication and, forexample, issue certificates (Cerberus etc.).

The mobile telephone with the transmitter electronics can be used as aprogramming device. A continuous data stream can be sent to the receiverwith the help of the transmitter electronics.

Future mobile telephones will perhaps be furnished with NFC, active orpassive RFID or low-power-wireless (for example as distributed under thebrand name Wibree™ (www.wibree.com)) or Ultra Low Power Bluetooth orother standards of identification. Through the use of the capacitiveresistive information transmission such an identification technology canbe integrated into a single device, and the user must not necessarilyknow which technology is in actuality used. Particularly interesting isthe combination of the approach according to the invention with otherthings, because for example the selective capacitive resistiveinformation transmission follows a short-range (<10 m) contactlessnonselective information transmission, and can work together with this.

Transmitter electronics for a mobile telephone can be designed accordingto standard dimensions and may be integrated in existing mobiletelephone architecture without further ado.

Furthermore, the remarks made with respect to FIG. 4 concerning radiofrequency signals and/or concerning interaction of RFID electronics withthe control electronics for the capacitive resistive coupling, can alsobe valid for the integration into a mobile telephone.

Electronic devices are often furnished with a shield for electromagneticfields, which protects the inner components of the device. These can,for example, be manufactured by sputter deposition technique on sectionsof the housing. According to an embodiment of the invention, now such ashield (“EMC shielding”) is arranged and contacted such that it can beused for the capacitive resistive coupling in the same manner as thefirst and second electrode. For example, the EMC shielding layer of thesecond housing part of a mobile telephone can be used as the first, oras the case may be the second electrode. This combination of thefunctionalities of “electrode for the capacitive resistive coupling” and“EMC shielding” is in particular unrestrictedly possible here, becausethe capacitive resistive signal frequencies proposed here are of lessthan 2 MHz, and are very small in comparison to the frequencies of thesignals, for example UHF-signals, from which the mobile telephoneelectronics are shielded. The capacitive resistive signal functionsquasi statically. For high frequencies the capacitance between the twoelectrodes functions like a short circuit of the electrodes against oneanother. Additionally, a parasitic capacitance and/or a capacitancespecifically envisioned for it can operate between the electrodes (or asthe case may be one of the electrodes) and a reference voltage (GND) asa virtual short circuit in relation to this reference voltage, while theelectrodes are decoupled from one another, and if relevant from thereference voltage, for the lower frequencies of the capacitive resistivecoupling.

FIGS. 7 to 9 relate to the further aspect of the invention and depictvery schematically electrode arrangements with non-parallel electrodefaces.

According to FIG. 7 two electrode pairs 71, 72 which stand at an angleto one another (at a right angle in the example shown) are present. Theelectrode pairs can be activated simultaneously or alternately or in anarbitrary sequence.

Other arrangements than those depicted are possible for such electrodepairs, for example in which the electrode pairs form four sides of acube, which also features the electronic component parts.

A disadvantage of a configuration with two orthogonal or nearlyorthogonal electrode pairs, is that large electrode faces must beaccommodated by a relatively large volume of the whole transmitter.

FIG. 8 depicts an arrangement with three electrodes 51, 52, 53, which incross-section form a triangle. The activated electrode pairs, betweenwhich the signal is generated, are for example, formed by the first andthe third electrodes 51, 53 and by the second and the third electrodes,52, 53.

FIG. 9 depicts an arrangement with three electrode faces, of which afirst and a second electrode face 61.1, 62.2 are formed by a common bentfirst electrode 61. The third electrode face 62 is formed by a secondelectrode 62 that is separate from the first electrode.

As described above, the electrodes are preferably held at as great adistance from one another as possible, and the dielectric constant ofthe medium(s) between the electrodes is as small as possible. Stillfurther aspects that are associated with as small an electricalconsumption as possible and/or the monitoring of the battery charge aredescribed with reference to FIG. 10. The components in the figure areoptional and can be present singly or in combination.

The transmitter electronics 7 according to FIG. 10 have a connection toan output device 41, which makes possible a status message of thebattery charge. Such a one can comprise a light emitting diode (LED) ormany light emitting diodes. Furthermore an activity detector 44 can bepresent, which turns off the electrode controls if the portable deviceis not moved. As an alternative or possibly as a replacement thereof, itcan also be imagined that the transmitter electronics are only active ifa wake up signal, for example an LF-wake up signal, is detected. Acorresponding detection unit is indicated by the reference numeral 45.Configurations with LF detectors for the starting-up of a circuit arealready known to those skilled in the art.

In the figure, an “on” switch 42 is depicted. Such a one can for examplebe employed if the electronics have been shut off in a “low comfortmode” because of a nearly-empty battery. Through actuation of the switchthe electronics are again activated for a limited time. Also depicted isan on-off switch, through which the whole portable device can be turnedoff if it is not needed. In the case of a connection to a “host system”(for example a mobile telephone) 31 the management of electricalrequirement is possibly somewhat less important.

The “turning-off of the electronics” does not preclude that individualcomponents from remaining active, for example the internal clock. By“turning-off” is expressly also meant the transition into such apartially active “sleep” mode.

1.-13. (canceled)
 14. A portable device for the transmission of signalsto a second device, wherein the portable device is wearable by a user,the portable device comprising: at least two electrodes and transmitterelectronics for the generation of an electrical signal between theelectrodes, such that the signal is able to be coupled into the body ofthe user by the electrodes of the first device and detected by at leastone electrode of the second device, the portable device furthercomprising at least one of the group comprising: component parts of thetransmitter electronics arranged between the electrodes, components ofanother application distinct from the transmitter electronics arrangedbetween the electrodes, and and an air gap between the electrodes. 15.The portable device according to claim 14, comprising an air gap betweenthe electrodes, wherein the air gap has dimensions that are matched tothose of an element distinct from the portable device, such distinctelement being able to be inserted into the air gap with an accurate fit.16. A portable device for the transmission of signals to a seconddevice, wherein the portable device is wearable by a user, the portabledevice comprising: at least two electrodes and transmitter electronicsfor the generation of an electrical signal between the electrodes, suchthat the signal is able to be coupled into the body of the user by theelectrodes of the first device and detected by at least one electrode ofthe second device, wherein the distance between the electrodes amountsto at least 1 mm.
 17. The portable device according to claim 16, whereinthe distance between the electrodes amounts to at least 1.5 mm.
 18. Theportable device according to claim 17, wherein the distance between theelectrodes amounts to at least 2 mm.
 19. The portable device accordingto claim 18, further comprising at least one of the group comprising:component parts of the transmitter electronics arranged between theelectrodes, components of another application distinct from thetransmitter electronics arranged between the electrodes, and and an airgap between the electrodes.
 20. The portable device according to claim14, comprising an air gap between the electrodes, the portable devicefurther comprising, in the air gap, a communications interface for theexchange of data between the portable device and a device that isdistinct from the portable device and can be inserted into the air gap.21. The portable device according to claim 14, wherein a communicationslink exists or can be formed between the transmitter electronics and aninput unit and the transmitter electronics are designed and/orprogrammed such that the electric signal is a function dependent uponthe data that is input into the input unit.
 22. The portable deviceaccording to claim 21, wherein component parts of an applicationdistinct from the transmitter electronics are arranged between theelectrodes, and wherein the portable device is designed as a mobiletelephone and the input unit is the input unit of the mobile telephone.23. The portable device according to claim 14, wherein at least one ofthe electrodes of the portable device is at least partially transparent.24. The portable device according to claim 14, further comprising anantenna for communication by means of induction or over electromagneticwaves.
 25. The portable device according claim 14, further comprising anactive or passive RFID transponder.
 26. The portable device according toclaim 25, further comprising a ferromagnetic element through whichelectromagnetic fields are able to be directed such that they arestrengthened in a region of an RFID antenna.
 27. The portable deviceaccording to claim 14, wherein the electrodes further function to shieldagainst electromagnetically interfering signals.
 28. The portable deviceaccording to claim 14, wherein the electrodes are in an arrangement ofelectrodes with electrode faces that are not parallel with one another.29. A method of controlling access to an object, the method comprisingthe step of: providing a portable device for the transmission of signalsto a second device, wherein the portable device is wearable by a user,the portable device comprising at least two electrodes and transmitterelectronics for the generation of an electrical signal between theelectrodes, such that the signal is able to be coupled into the body ofthe user by the electrodes of the first device and detected by at leastone electrode of the second device, the portable device furthercomprising at least one of the group comprising: component parts of thetransmitter electronics arranged between the electrodes, components ofanother application distinct from the transmitter electronics arrangedbetween the electrodes, and and an air gap between the electrodes, themethod comprising the further steps of using the portable device fortransmitting authentication information between the first and the seconddevice, and of using the authentication information to control theaccess.